Laser treatment cooling head

ABSTRACT

A cooling head for attachment to a skin treatment laser has a metal body with a mount at one end for attachment to a laser head to secure the metal body to the head. A cooling surface at the other end is for application to a patient&#39;s skin and has an aperture therethrough. A bore extends from the mount through the body to the aperture in the cooling surface to allow a laser beam to be passed therethrough to a treatment area of the patient&#39;s skin. An extraction port enables removal of debris from the treatment area and for connection to a vacuum source. An optically transparent window is disposed in the body to allow the treatment area to be viewed. A cooling means (liquid flow heat exchanger, Peltier device) enables heat removal from the body in use in order to cool the cooling surface. A method of skin treatment employs the cooling head to cool the area surrounding the treatment area to reduce pain and protect the skin of the patient.

The present invention relates generally to means of cooling the surfaceof skin during laser treatment (for example, for so-called laserresurfacing), the aim being to reduce the sensitivity to pain, reducethe need for anaesthetic or both. More particularly, the presentinvention relates to a laser treatment cooling head and, particularly,to a cooling head which can be used with a CO₂ or other laser employedfor laser treatment of a patient's skin.

The advent of easily usable laser equipment has led to a great increasein this kind of treatment, but the problem of the control of pain, whichcan be severe as the process is essentially one of burning away skin,remains an obstacle to the wider use of the technique. In particular,according to clinical judgment and patient tolerance of pain, a generalor local anaesthetic may be necessary. The use of a general anaestheticenables the clinician to proceed rapidly with the treatment withoutconstant checking of the comfort of the patient, but carries the severedrawbacks of the well known trauma of general anaesthetics, includingthe risk and the need for a recovery time before the patient resumesnormal life, the need for an anaesthetist and the time for preparationand recovery. The latter two, in particular, make the cost of thetreatment very high. In contrast, use of a local anaesthetic can allow adermatologist to administer the anaesthetic, but again there aredrawbacks. Pain control over certain areas of the body, particularly theface, requires multiple injection sites which is traumatic for thepatient and the need for top-up doses during treatment is alsounpleasant for the patient, also slowing down the treatment. The totaldose of local anaesthetic is also limited which can therefore limit aparticular treatment session, thus requiring further sessions andassociated increased cost.

It has been proposed to use localised cooling to overcome the problemsof anaesthesia and, in particular, it has been proposed to utilise aflow of coolant through a laser-transparent glass chamber which can beheld against the skin while the laser treatment is carried out. However,this is only possible with visible light lasers, not with CO₂, ErbiumYAG (yttrium aluminium garnet), or Holmium lasers, as existing coolingdevices use coolants and windows that are not lucent to the wavelengthsof CO₂, Erbium YAG, or Holmium radiation, i.e. current cooling devicesusing water would absorb the energy at these wavelengths so skintreatment would be impossible.

According to a first aspect of the present invention, there is provideda cooling head for a skin treatment laser, the cooling head comprising

a metal or other thermally conductive body having

a mount disposed at one end for attachment to a laser head to secure themetal body relative to the head in a fixed position;

a cooling surface at the other end for application to a patient's skinand having an aperture therethrough;

a bore extending from the mount through the body to the aperture in thecooling surface to allow a laser beam to be passed therethrough to atreatment area of the patient's skin;

an extraction port for enabling removal of debris from the treatmentarea and for connection to a vacuum source; and

an optically transparent window disposed in the body to allow thetreatment area at the aperture in the cooling surface to be viewed by asurgeon using the laser; and

a cooling means provided in or on the body to enable heat removal fromthe body in use in order to cool the cooling surface.

The cooling means may be a coolant passage for example or an electroniccooling means such a Peltier device. For increased flexibility of use,both may be incorporated and used together or separately, say atdifferent times during treatment.

Using a metal body enables a relatively large mass of cold material tobe provided as, in effect, a store of refrigerated material, ensuringthat cooling around the treatment area can be maintained with a highdegree of certainty. The mount may be integral with or separate to themetal body itself.

The optically transparent window disposed in the body may, at itssimplest, be provided by simple open section, slot, bore or otheraperture in the side wall of body which may be angled towards theaperture in the cooling surface or otherwise provide a line of sight tothe aperture. For example, the body may be substantially C or U-shapedin cross-section, ie part of the side wall being either removed or elsebeing left out during manufacture to allow direct vision of the insideof the body and the treatment area, in which case, the aperture at theother end of the body may be co-extensive with the window. In analternative construction the optically transparent window may be solid,eg glass, and may be a lens.

Preferably, when a coolant passage is employed, it comprises one or morecoolant pathways either formed through the metal body or disposed on theexterior of the metal body in intimate contact with the body, to form aheat exchanger. For example, the coolant passage may comprise ahelically wound copper tube soft-soldered in contact with a brass body.The coolant may be simply water, brine or another liquid refrigerant andis preferably designed to maintain the cooling surface, ie the contactpoint of the cooling head with the patient's skin, at a temperature ofbetween −20° C. and +4° C., which temperature may be arranged to beadjustable. However, in an alternative construction, the pathways forcoolant may be provided directly within the metal body and the coolantmay be a low temperature, laser lucent, gas such as nitrogen (which islucent to CO₂, Erbium YAG, or Holmium laser wavelengths), in which casethe nitrogen may be provided to the central bore and may be removedthrough the extraction port together with debris, by a suitable vacuumpump or the like.

Particularly in constructions where the coolant flows within the head,feedback temperature control of the head may be provided so that thesurgeon can set a temperature which is a compromise between the feelingof discomfort from the cold and the laser. The temperature rangeavailable should be −20° C. to +4° C. The feedback system may compriseone or more temperature sensors in the head so that the temperature orflow rate or both of the coolant can be adjusted to maintain the desiredtemperature. For convenience the temperatures of one or more sites inthe head can be displayed electronically to the surgeon.

Providing an extraction port to allow extraction of debris and debrisvapour reduces the risk of pollution of the treatment area with debrisvapour.

According to a second aspect of the present invention, there is provideda cooling head for a skin treatment laser, the cooling head comprising

a body having

a mount disposed at one end for attachment to a laser head to secure thebody relative to the head in a fixed position;

a surface at the other end for application to a patient's skin andhaving an aperture therethrough;

a coolant passage through the body to enable a fluid coolant to bepassed to a treatment area of the patient's skin through the surface, inuse in order to cool the patient's skin;

an extraction passage through the body for enabling removal of coolantand debris from the treatment area;

a bore or passage extending from the mount through the body to theaperture in the cooling surface to allow a laser beam to be passedtherethrough; and

an optically transparent window disposed in the body to allow thetreatment area at the aperture in the surface to be viewed by a surgeonusing the laser.

In a first embodiment, the coolant passage connects with the aperture inthe surface to enable coolant to be provided to the patient's skin atthe point of application of the laser beam. This is preferably achievedby forming the surface of the body simply from the contiguous end facesof a sidewall or sidewalls, defining the sides of a chamber which formsthe coolant passage, so that the aperture is provided as the open end ofthe chamber between the sidewall end faces.

In a second embodiment, the coolant passage passes through the body andthe surface at a location adjacent the aperture to enable coolant to beprovided to the patient's skin adjacent the point of application of thelaser beam.

In both cases, the body may be at least partly formed of metal adjacentthe surface in order to enable the surface to be cooled by the flow ofcoolant through or around the body so as to provide an additionalmeasure of cooling to the patient's skin by the application of thecooled surface to the skin.

A CO₂ laser would be incapable of use with the prior art systemsmentioned above and therefore the present invention enables the directapplication of, for example, CO₂, Erbium YAG, or Holmium laser energy tothe skin, whilst ensuring that both satisfactory cooling and requiredvisibility for the surgeon are maintained.

The optically transparent window disposed in the body may be provided bya windowed aperture in an angled side wall of body facing towards theaperture in the cooling surface. The optically transparent window may besolid, eg glass and may be in the form of a lens to magnify thetreatment area.

Preferably the mount comprises an annular counter-bore at the open endof the bore and has fastenings for securing a laser head in a definedposition within the counter-bore.

The surface applied to the patient's skin may be substantially flat orsignificantly curved, depending on the precise application, ie theparticular area of the skin to be treated. For example, when treatingsignificantly concave areas of the skin, such as adjacent the nose, aconvex surface in necessary in order that as much of the surface aspossible can engage the skin to provide an effective seal with the skin.

Preferably, the coolant passage according to the second aspect of theinvention, comprises inlet and outlet ports and an internal chamberformed within the body and opening to the patient's skin through thesurface. The coolant may be a low temperature gas such as nitrogen whichmay be removed through the extraction port together with debris, by asuitable vacuum pump or the like.

A light may be provided within the chamber to illuminate the treatmentarea.

Various examples of cooling heads according to the present inventionwill now be described with reference to the accompanying drawings inwhich:

FIG. 1 is a first side elevation of a first cooling head;

FIG. 2 is a second side elevation at 90° to the first;

FIGS. 3 and 4 are end elevations on FIG. 1;

FIG. 5 is an isometric view with the coolant pipe removed;

FIG. 6 is an exploded view of a modification of the example shown inFIGS. 1 to 5;

FIGS. 7A-D show views of the assembled modified head from differentpositions

FIG. 8 is an exploded view of a further, third, variant;

FIG. 8A is an isometric view of an alternative contact head for thethird variant;

FIG. 9 is an exploded view of a fourth example;

FIGS. 10 to 13 are perspective, end, side and longitudinal section viewsof the fourth example;

FIG. 14 is an exploded view of a fifth example; and

FIGS. 15A-D show views of the assembled fifth head from differentpositions.

The cooling heads 1 shown in FIGS. 1 to 7 of the drawings comprises agenerally cylindrical brass body 2 having, at one end, a laser mount 3in the form of an enlarged annular lip and, at the other end, asquare-sectioned cooling surface 4. Disposed along the longitudinal axisof the cylindrical body 2 is a bore 5 which extends through the coolingsurface 4 at a square aperture 6 and which extends through the annularlip forming the mount 3 within which there is formed a counter-bore 7 ofdiameter greater than the bore 5 for accurate and secure location of thelower end of a laser housing (not shown).

A brass tube 8 is soft-soldered into a side bore 9 to provide forextraction of debris in use, and an inclined bore 10 which provides aviewing window, extends through the wall of the body 2 on the sideopposite the tube 8. As can be seen best from FIGS. 1 and 2, theinclined bore 10 is directed towards the aperture 6. This enables thesurgeon to view the area of skin being treated whilst treatment isactually taking place. Helically wound around the cylindrical brass body2 is a copper pipe or tube 11 through which a refrigerant is passed inorder to achieve cooling of the body 2.

In use, the body is pre-cooled my means of the flow of refrigerantthrough the tube 11, whilst attached to the laser head through the mount3, and the cooling surface 4 is then applied to the skin of the patientto cool the area of treatment. A suitable vacuum pump attached to thetube 8 is then switched on and the laser actuated as required to treatthe skin, debris from the skin being removed through the tube 8.Refrigerant continues to flow through the tube 11 to maintain the body 2at the desired low temperature in order to desensitise the skin of thepatient while the treatment is taking place.

The same reference numerals for component parts are used whereappropriate in the drawing of the modification shown in FIGS. 6 and 7A-Dand similar parts will not be described again. The modification has amulti-part body 2 which comprises a main part 20 to which is attached acontact head 21, by means of a locking ring 22 secured to a lip 23 onthe main part 20, by means of a suitable quick thread or similar forexample. This allows different contact heads to be used for applicationto different areas of the body having different skin curvatures, toenable contact to be maximised and hence cooling optimised.

Such contact heads may include different apertures through which thelaser beam passes in use to the skin, e.g., a range of sizes say from 2to 10 mm may be provided. Additionally, the aperture may be offset fromthe centre of the head to provide an increased cooling surface on oneside, so that increased cooling can be provided in advance of thepassage of the laser beam over the treatment area. Different shapes andthicknesses may be utilised to allow treatment of sharply curved areasof skin, eg on the nose.

The head may be anatomically shaped to suit particular areas. Thecontact head may be articulated to allow the head to move smoothly overanatomical obstacles and contours (eg from cheek to nose) more easilywhilst maintaining intimate skin contact. The head may be arranged torotate, for example, between specific indexed orientations, to enablethe direction of traverse to be changed without having to rotate thewhole body.

Furthermore, the contact head may be made as a disposable component.

In the modification, the viewing port has a tubular sleeve 100 securedwithin it, with a transparent window 101 being provided at the free endof the sleeve. The window may be a lens to provide magnification of thetreatment site.

Three locking screws 70 serve to locate the lower end of a tubularhousing 12 of the laser within the counter-bore 7.

The coolant circuit may be as shown in the first example, oralternatively, may be formed from one or more internal passages in thebody 2.

As mentioned, electrical cooling may be provided by controlling thecurrent applied to a Peltier device mounted in the body and this coolingtechnique may be used alone or in conjunction with fluid cooling.

FIG. 8 shows an exploded view of a third variant in which the mount 3 isseparated from the metal body 2 by a plastics or ceramic insulator 24and the body is formed in two parts 25, 26 , the second part 26 of whichis C-shaped in cross-section to provide a window in the form of an openside which increases the ability to view the treatment area. Theinsulator 24 and first body part 25 are chamfered to improve the viewthrough the open side of the body part 26. Fittings 29 provide inlet andoutlet ports for fluid coolant to the body part 26 and a port 8 provdesan extraction point for debris. The contact head 4 is in the form of arectangular plate with a centrally disposed aperture 6. Screws 27, 28are used to fix the various components together. The modification of thecontact head 4 shown in FIG. 8A shows an offset aperture in the form ofa slot 6′ at one edge of the contact head which, again, is in the formof a plate.

FIGS. 9 to 13 show a fourth example which includes a Peltier electroniccooling device as well as fluid cooling. The construction of thisexample has a stack of components (similar to the third example) whichinclude a clamping ring 3 providing a mount for the laser tube (notshown). The body 2 has plural component elements 201-209 which are heldtogether by screws 27, 28. An insulating body part 201 has an extractionport 8, supports the clamping ring 3, and sits between it and three heatsink components 202-204. Coolant ports 29 attach to the heat sink 204. APeltier device 205 (with a central hole to permit the unimpeded passageof laser radiation to the skin) lies adjacent to the component 204 andis clamped to it by a clamping plate 206. A locking ring 207 is capturedbetween the clamping plate 206 and a flanged sleeve 208 which issoldered to the clamping plate 206. An open-sided spacer sleeve 209 towhich a contact plate 4 is soldered is attached to the other body partsvia the locking ring 207. This example allows either or both of aPeltier and fluid cooling to be used at different times during thetreatment process, for example, it may be useful to pre-cool the deviceby means of the fluid cooling system and then operate the Peltier systemduring the actual treatment process itself while the head is applied tothe skin of the patient. FIG. 13 shows that this construction provides a35° viewing angle A for the surgeon.

The cooling head 1 shown in FIGS. 14 & 15A to D comprises a generallybox-like die-cast or injection moulded body 2 having an annular mountinglip 3 on its top and at the other end a square-sectioned cooling surface4 formed by the contiguous end faces of sidewalls 21-24 of the body withan aperture 6 formed between the end faces of the sidewalls 21-24.Within the body 2 is a chamber 5 which extends from the annular lip,connecting with it through a bore or passage 7, and being open at thebottom through the end surface 4.

The annular lip 3 provides for accurate and secure location of the lowerend of a laser housing 12, three locking screws 70 serving to locate thelower end of the tubular housing 12 for the laser within the bore orpassage 7.

A pair of tubular coolant ports 8, 9 are fixed to the sidewalls 21, 23respectively at corresponding apertures 81, 91 to provide for the inflowand outflow of coolant to the chamber 5, the outlet port 9 alsoproviding for extraction of debris in use.

An inclined bore sidewall 25 has a circular aperture 10 into the chamber5, which thus provides for a viewing window. Within the aperture 10 isfitted a lens 100, held in place by a circlip 101 and sealed to the sideof the aperture with an O-ring synthetic rubber seal 102. The aperture10 is directed towards the aperture 6 to enable the surgeon to view,with slight magnification, the area of skin being treated whilsttreatment is actually taking place.

In use, the body is pre-cooled by means of the flow of refrigerantthrough the chamber 5 (which may be augmented by an electrical coolingdevice such as a Peltier), whilst attached to the laser head housing 12,and is then applied to the skin of the patient to cool the area oftreatment, debris from the skin being removed through the tubular outletport 9 togther with spent coolant, which may be filtered and re-cooledfor re-circulation through the chamber 5.

To increase visibility of the treatment area, a light 50 can be providedinside the chamber 5, by means of a suitable LED 51 mounted on a tube 52extending into the chamber through an aperture 53 in the sidewall 23.

What is claimed is:
 1. A cooling head for a skin treatment laser, thecooling head comprising a metal or other thermally conductive bodyhaving a mount disposed at one end for attachment to a laser head tosecure the body relative to the head in a fixed position; a coolingsurface at the other end for application to a patient's skin and havinga aperture therethrough; a bore extending from the mount through thebody to the aperture in the cooling surface through respective open endsto allow a laser beam to be passed therethrough to a treatment area ofthe patient's skin; an extraction port for enabling removal of debrisfrom the treatment area and for connection to a vacuum source; and anoptically transparent window disposed in the body to allow the treatmentarea at the aperture in the cooling surface to be viewed by a surgeonusing the laser; and a cooling means provided in or on the body toenable heat removal from the body in use in order to cool the coolingsurface.
 2. A cooling head according to claim 1, wherein the coolingmeans comprises a coolant passage.
 3. A cooling head according to claim2, wherein the coolant passage comprises one or more coolant pathwaysformed through the body or disposed on the exterior of the metal body inintimate contact with the body, to form a heat exchanger.
 4. A coolinghead according to claim 1, wherein the cooling means comprises anelectronic cooling means.
 5. A cooling head according to claim 4,wherein the electronic cooling means comprises a Peltier device.
 6. Acooling head according to claim 1, wherein the body has a side wall, andthe optically transparent window disposed in the body comprises an opensection in the side wall of the body.
 7. A cooling head according toclaim 6, wherein the open section comprises an aperture, said aperturebeing angled towards the aperture in the cooling surface.
 8. A coolinghead according to claim 1, wherein the optically transparent windowdisposed in the body comprises a solid transparent element.
 9. A coolinghead according to claim 1, wherein the mount has an annular counter-boreat the respective open end of the bore and has fastenings for securing alaser head in a defined position within the counter-bore.
 10. A coolinghead for a skin treatment laser, the cooling head comprising a bodyhaving a mount disposed at one end for attachment to a laser head tosecure the body relative to the head in a fixed position; a surface atthe other end for application to a patient's skin and having an aperturetherethrough; a coolant passage through the body to enable a fluidcoolant to be passed to a treatment area of the patient's skin throughthe surface, in use in order to cool the patient's skin; an extractionpassage through the body for enabling removal of coolant and debris fromthe treatment area; a bore or passage extending from the mount throughthe body to the aperture in the cooling surface to allow a laser beam tobe passed therethrough; and an optically transparent window disposed inthe body to allow the treatment area at the aperture in the surface tobe viewed by a surgeon using the laser.
 11. A cooling head according toclaim 10, wherein the coolant passage connects with the aperture in thesurface to enable coolant to be provided to the patient's skin at thepoint of application of the laser beam.
 12. A cooling head according toclaim 11, wherein the body is at least partly formed of metal adjacentthe surface in order to enable the surface to be cooled by the flow ofcoolant through or around the body.
 13. A cooling head according toclaim 10, further comprising an electronic cooling means.
 14. A coolinghead according to claim 13, wherein the electronic cooling meanscomprises a Peltier device.
 15. A cooling head according to claim 10,wherein the body has a side wall, and the optically transparent windowdisposed in the body comprises an open section in the side wall of thebody.
 16. A cooling head according to claim 15, wherein the open sectioncomprises an aperture, said aperture being angled towards the aperturein the cooling surface.
 17. A cooling head according to claim 10,wherein the optically transparent window disposed in the body comprisesa solid transparent element.
 18. A cooling head according to claim 10,wherein the coolant passage passes through the body and the surface at alocation adjacent the aperture to enable coolant to be provided to thepatient's skin adjacent the point of application of the laser beam. 19.A cooling head according to claim 10, wherein the coolant passagecomprises inlet and outlet ports and an internal chamber formed withinthe body and opening, to the patient's skin, through the said surface.20. A cooling head according to claim 10, wherein the mount comprises anannular counter-bore at the respective open end of the bore and hasfastenings fro securing a laser head in a defined position within thecounter-bore.
 21. A method of cooling an area of a patient's skinsurrounding a treatment area to reduce or eliminate pain, or tissuedamage around the treatment area during skin surgical treatment thereto,the method comprising the steps of: applying a cooling surface to apatient's skin, the cooling surface having an aperture therethrough toallow treatment to be effected therethrough to the treatment area of thepatient's skin; passing a cooling fluid into thermal contact with thecooling surface the cooling fluid being isolated from the treatmentarea; and thereby cooling the cooling surface whereby the area of thepatient's skin surrounding the treatment area is cooled.
 22. A method ofsurgical skin treatment, the method comprising the steps of applying acooling surface to an area of a patient's skin surrounding a treatmentarea, the cooling surface having an aperture therethrough to allowtreatment to be effected therethrough to the treatment area of thepatient's skin; passing a cooling fluid into thermal contact with thecooling surface the cooling fluid being isolated from the treatmentarea, thereby cooling the cooling surface whereby the patient's skin iscooled around the aperture; and simultaneously with said cooling,carrying out a surgical skin treatment procedure to the treatment are ofthe patient's skin through the aperture, whereby pain, or tissue damagearound the area of treatment are reduced or eliminated by the action ofcooling the patient's skin around the area of treatment.
 23. A method ofcooling an area of a patient's skin surrounding a treatment area duringskin surgical treatment to reduce or eliminate pain, or tissue damagearound the treatment area, the method comprising the steps of: applyinga cooling surface to a patient's skin, the cooling surface having anaperture therethrough to allow treatment to be effected therethrough toallow treatment to be effected therethrough to the treatment area of thepatient's skin; passing a cooling fluid into thermal contact with thecooling surface and to the skin adjacent the cooling surface the coolingfluid being isolated from the treatment area; and thereby cooling thecooling surface and the area of the patient's skin surrounding theaperture.
 24. A method of surgical skin treatment, the method comprisingthe steps of: applying a cooling surface to an area of a patient's skinsurrounding treatment area, the cooling surface having an aperturetherethrough to allow treatment to be effected therethrough to thetreatment area of the patient's skin; passing a cooling fluid intothermal contact with the cooling surface and to the skin adjacent thecooling surface the cooling fluid being isolated from the treatmentarea; thereby cooling the cooling surface whereby the area of thepatient's skin surrounding the treatment area is cooled; andsimultaneously with said cooling, carrying out a surgical skin treatmentprocedure to the patient's skin through the aperture, whereby pain, ortissue damage around the treatment area are reduced or eliminated by theaction of cooling the patient's skin surrounding the treatment area.